Germicidally active deionizing agents for alkaline ph solutions



Patented Oct. 3, 1950 AGENTS FOR ALKALINE TIONS DH SOLU- Frederick C.Bersworth, Verona, N. J.

No Drawing.

Continuation of application Serial No. 713,078, November 29, 1946. Thisapplication September 16, 1947, Serial No. 774,421

Claims.

This invention relates to laundering operations wherein soiled clothesare agitated in hot aqueous alkaline pH solutions containing watersoluble alkali metal-fatty acid soap compounds to free the soiling dirtfrom the clothes and to suspend the dirt in the aqueous solutionfollowed by draining oil? the major portion of the dirty soap solutionand rinsing one or more times in clear water to remove the remainingdirty soap solution from the washed clothes.

In such general process, as the remaining dirty soap solution is dilutedwith water during the first rinsing step, the dirt particles suspendedin the soap solution tend to re-precipitate upon the clean clothes alongwith insoluble metal soap compounds formed by reaction of the alkalimetal soap compounds with the soluble salts present in the rinse waterand metal hydroxides precipitated in such alkaline pH solutions. Thisreaction imparts a grey tinge to the clean clothes which subsequentlymust be removed by blueing" and souring rinses, common in the art.

In addition, commercial laundry practice requires the use ofdisinfectants and bactericidal agents to prevent the spread of diseasein laundry, obtained from a plurality of sources, washed in the samesoap solutions.

The object of the present invention is to provide a germicidallyactive-deionizing agent for use in the laundering of clothes,particularly during the rinse removal of remaining dirty soap solutionsfrom the clothes.

Another object is to facilitate the laundering of clothes by the use ofa germicidally activedeion'izing rinsing agent inhibiting theprecipitation of dirt, insoluble soap compounds and metal oxides uponthe clothes during the washing and rinsing operations and eliminatingthereby the necessity of subsequently treating the clothes to removesame or to overcome the effect of same and to sterilize the saidclothes.

A further object is to provide a germicidally active-water deionizingagent for use in alkaline pH solutions and in the presence of alkalimetal soap compounds.

Still another object is to provide a germicidally active detergentconsisting of a mixture of water soluble soap compounds and a germicidalquaternary ammonium compound.

Other objects will be apparent as the invention is more fullyhereinafter disclosed.

In accordance with these objects I have discovered that the monototetra-quaternary ammonium salts of ethylene diamine tetraacetic acid arestrong germicidally active compounds 2 soluble in alkaline pH solutionsand stable in said solutions in the presence of alkali metalfatty acidsoap compounds.

I have further discovered that the monoquaternary ammonium salt ofethylene diamine tetraacetic acid after neutralizing the remainingcarboxylic acid groups with caustic alkali is, in addition to beinggermicidally active, a strong deionizing agent in aqueous: solutionsfunctioning to remove from such aqueous solutions metal ions tending toprecipitate insoluble soapcompounds and to solubilize such basic metalions precipitatable in such alkaline pH solutions as basic oxides,hydroxides and carbonates.

Further, I have discovered. that the monoquaternary ammonium salt ofethylene diamine tetraacetic acid in which the primary carboxylic groupof the second amino group has been esterified by reaction with a monoorpoly alcohol and the two remaining secondarycarboxylic groups havebeen neutralized by caustic alkali is, in addition to being germicidallyactive, 9. more powerful deionizing agent and precipitatesolubilizingagent than the mono-quaternary ammonium-tri-alkali' metal salt ofethylene diamine tetraacetic acid.

Furthermore, I have discovered that these quaternary ammonium compoundsare compatible in all proportions with water soluble soap compounds andthat germicidal mixtures thereof may be formed with the quaternaryammonium compound of the mixture also functioning therein as ananti-oxidant,

These discoveries as to the chemical properties of the above identifiedquaternary ammonium salts of ethylene diaminetetraacetic acid have ledme to adapt the same as germicidal-deionizing agents for use inassociation with water soluble soap compounds, particularly alkalimetal-fatty acid soap compounds, and as one specific embodiment thereofI will disclose the invention as it is adapted for utility in thelaundering of clothes. Each of the compounds, above identifled. aremiscible in all proportions with alkali metal-fatty acidsoap compoundsand are freely soluble in alkaline pH solutions containing alkali metalsoap compounds.

The present invention contemplates the incorporation of said quaternaryammonium salts of ethylene diamine tetraaceticcacid in soap (bar,powder, flake or liquid) forming thereby a. bactericidally activedetergent composition having strong deionizing properties, and alsocontemplates the use of the said quaternary ammonium salts as deionizingand baetericidally active addition agents to water or to alkaline pHsolutions or to such solutions containing alkali metalfatty acid soapcompounds, such as during the rinsing of the washed clothes to free theclothes of remaining dirty soap solutions.

As a specific embodiment of the invention, but not by way of limitation,I will describe the same as it has been adapted to use in standardlaundry practice in the case of a specific quaternary ammonium compoundknown in the art under the trade name Safran and chemically as dimethylbenzyl lauryl ammonium chloride. This particular quaternary ammoniumcompound has heretofore in the art been recognized as a strongantiseptic and bactericidal agent. In alkaline pH solutions and inaqueous solutions of alkali metaliatty acid soap compounds, however, thecompound is known to be inactivated and precipitated, respectively.

The mono-quaternary ammonium salt of ethylene diamine tetraacetic acidis preferably formed from this specific quaternary ammonium compound byreacting the quaternary ammonium hydroxide with the amino acid. Theamino acid is insoluble in water but dissolves readily in an aqueoussolution of the quaternary ammonium hydroxide. The mono-quaternaryammonium salt is formed by dissolving one molar weight of the amino acidin an aqueous solution containing one molar weight of the quaternaryammonium hydroxide. The amount of water present in the solution may bewidely varied without essential departure from the invention.

The resulting aqueous solution of the monoquaternary ammonium salt ofethylene diamine tetraacetic acid is neutralized with 3 molar weights ofcaustic alkali (NaOH) and the resultant mono-quaternaryammonium-tri-alkali metal salt of ethylene diamine tetraacetic acid isrecovered from the aqueous solution by evaporating oil the water ofsolution.

The white dry-powder salt recovered may be added to the alkaline pH soapsolution used in washing thedirty clothes or may be incorporated in thesoap detergent employed in forming said soap solution, as may bedesired.

I have found it preferable to incorporate from a small percent up to ofthe quaternary ammonium-tri-alkali metal salt of ethylene diaminetetraacetic acid in the soap detergent before the addition of the soapto the washing solution. Alternatively, the same eifect is produced byadding from a small percent up to 10% (by weight of the soap detergentadded) of the quaternary ammonium-tri-alkali metal salt to the waterused in forming the soap solution prior to the addition of the soapcompounds thereto.

The incorporation of the quaternary ammonium salt in the soap detergentor the addition of the quaternary ammonium salt to the water prior tothe addition of the soap compounds thereto, insures against theprecipitation of insoluble soap compounds by reaction of the soapcompounds with hardening constituents present in the water and preventsthe precipitation of insoluble metal oxides and hydroxides in thealkaline pH washing solution thus formed.

The reaction by which the precipitation of insoluble soap compounds andinsoluble metal oxides and hydroxides is inhibited by the quaternaryammonium salt is quite complex and difiicult to represent by chemicalequations. In general, ethylene diamine tetraacttic acid, is a strongchelate-forming compound in aqueous solution and this chemical propertyis believed to be the major chemical property which stabilizes thepresent salt in aqueous solution under the widely varied conditions oftemperature, concentration of salt, amount and kind of waterhardeningconstituents present, etc., normally encountered in laundry operations.Suflice it to say, however, that the quaternary ammonium salt isextremely stable in alkaline pH solutions as the quaternary ammonium ionis not displaceable by the lesser basic alkali metal or other positivemetal ions present in the solution under the conditions of extremedilution of the quaternary ammonium salt in the washing solution or theconcentration of sodium ions present therein. However, the complex aminoacid negative ion of the compound, in its highly ionized condition orstate in the solution, is highly unstable and extremely reactivechemically at the other carboxylic acid groups with all other basicmetal ions present in the solution. This chemical activity is believeddue to the liberation, upon ionization, of the residual valenciesnormally present on the pentavalent nitrogen atom of each amino groupwhich residual valencies attract to the nitrogen positive and negativeions present in the solution to stabilize the nitrogen atomin itspentavalent state. While the positive metal ions cannot displace thequaternary ammonium and alkali metal positive ions in the carboxylicgroups of the salt, they can and do satisfy the released valencies onthe pentavalent nitrogen atoms in the amino acid negative ion. Suchcomplex compounds are with difliculty decomposed by free alkali even attemperatures ap proximating the boiling point of water in such washingsolutions. Many other amino polycarboxylic acids are chelate-formingcompounds to a greater or lesser degree and may be substituted in partor in whole for ethylene diamine tetraacetic acid without departure fromthe present invention, as one skilled in the art will recognize.

The addition of from a small percent as low as 1% up to 10% of thisquaternary ammoniumtri-alkali metal salt (based on the weight of thesoap compounds added) to the water of the alkaline pH solution, prior toor simultaneously with the addition of the soap compounds theretocompletely deionizes water of average hardness and mineral content sothat the precipitation of insoluble metallic soap compounds and basicmetal compounds is inhibited complete y.

Following usual washing operations involving agitation of the dirtyclothes in the soap solution to free the soiling dirt from the clothesand to suspend the same in the soap solution, the dirty soap solution isdrained ofi from the washed clothes as heretofore practiced. One or moreof the washing operations may be practiced, if desired or deemednecessary, to remove all of the soiling dirt from the clothes.

The washed clothes containing the residual dirty soap solution left fromthe last or final draining operation are then agitated one or more timesin water containing said monmquaternary ammonium-tri-alkali metal saltof ethylene diamine tetraacetic acid to free the clothes from theresidual dirty soap solution. The amount of said salt to be added to therinse water may vary widely, from a small amount to a large amountdepending upon the amount of water hardening constituents presenttherein and the amount of precipitatable metal ions present in thesolution. Usually 5 to 10 grams per gallon of water is ample protectionin the case of water conper gallon of water used is ample to completelydeionize the water and to impart thereto high germicidal activity.

This amount of the salt should be added to each rinse water for bestresults. After thorough rinsing in at least two rinse waters, theclothes 3:

may be wrung dry and hung up to dry as per usual practice withoutfurther treatment by blueing or souring or disinfecting as heretoforepracticed.

As an alternative and more effective agent to that above described, oneof the remaining carboxylic groups of the mono-quaternary ammonium salt,above identified, is first esterifled with a monoor poly-alchol and themonoquaternary ammonium-ester then is neutralized with caustic alkali toform a mono-ester, monoquaternary di-alkali metal salt of ethylenediamine tetraacetic acid. This compound is even more eifective as adeionizing agent and germicidal agent in alkaline pH solutions and inalkaline pH solutions containing alkali metal soap compounds than themono-quaternary tri-alkali metal salt of the above specific embodiment.

To form this salt, one molar reacting weight of a poly-alcohol, such asglycerine, is added to the aqueous solution of the mono-quaternaryammonium salt formed as above described and the solution is heated undera high vacuum to drive off the water present and to complete theesterification reaction. The resulting monoester-mono-quaternaryammonium salt product is redissolved in water, the remaining carboxylicacid groups neutralized with caustic alkali and the water of solution isagain removed by evaporation to dryness.

This compound is completely miscible in all proportions with soapcompounds and is highly soluble in water and is extremely stable inrelatively high alkaline pH solutions at temperatures up to the solutionboiling point.

In laundry operations this ester compound may be used in about the sameproportions as here inabove specified for the mono-quaternaryammonium-tri-alkali metal salt compound and in the same manner withbetter and more eflicient results both as a germicidal agent and as adeionizing agent.

As a second alternative compound I may employ a mixture consisting of arelatively small amount of the tetra-quaternary ammonium salt ofethylene diamine tetraacetic acid and a large amount of the quaternaryammonium base. Usually to of the salt per unit weight of the mixturegives the best results.

As a third alternative I may employ a mixture consisting of a relativelysmall amount of the mono-quaternary ammonium salt and a relatively largeamount of the tetra sodium salt of ethylene diamine tetraacetic acid.Usually 10% to of the salt per unit weight of the mixture gives the bestresults.

The mixture of the second alternative above given has unusually stronggermicidal properties and exceptionally strong deionizing propertiesbeing unusually efiective as a deionizing agent for calcium salts. Inthe presence of large amounts of alkali metal-fatty acid soap compounds,however, some precipitation of insoluble quaternary ammonium-fatty acidsoaps may be obtained and the use of this compound generally isrestricted to rinsing operations in the substantial absence of fattyacid soap compounds.

The mixture of the third alternative, however,

is utilizable in the presence of alkali-metal fatty acid soap compoundsbeing a stronger deionizer agent than the mono-quaternary ammonium salt.In water of exceptional hardness this mixture is preferred in thewashing and rinsing solutions, the amount used in the rinse water beingincreased to from 10 to 20 grams per gallon in order to obtainequivalent germicidal activity.

Another mixture oifering wide utility in the art is a mixture consistingof the quaternary ammonium compound and the tri-alkali metal salt ofethylene diamine tetraacetic acid containing about 10% to 20% of thetri-alkali metal salt. This mixture appears to be about 3 times asstrong a deionizing agent as the tetra-alkali metal salt of ethylenediamine tetraacetic acid and to be extremely stable in high pH solutionsin addition to having strong bactericidal prop erties. The mixtureappears compatible in all proportions with alkali metal soap compoundsin the dry state or in aqueous solutions, contrary to expectations.

The efliciency of the compounds above described as germicidal agents isdifiicult to establish due to the great variation of conditions involvedin commercial and domestic laundry practices. However, experimentaltests have indicated that the quaternary ammonium salts above describedare strong bactericidal agents equal to or superior to otherbactericidal agents under identical test conditions and the bactericidalactivity of the compounds is unaffected by anionic compounds such asalkali metal-fatty acid soap compounds. Many tests on clothes washed andrinsed in the presence of these compounds have shown complete sterilityas to bacteria and fungi commonly present in and on such dirty wearingapparel.

It is believed apparent from the above disclosure that any otherbactericidally active: quaternary ammonium compound may be substitutedfor "Safran in the above specific examples given Without essentialdeparture from the present invention, such as those known in the artunder the trade name "Hyamine 1622 and Roccal, the composition of whichvaries somewhat as the positive ion of all such quaternary ammoniumcompounds are characterized by being strong bactericidal agents and bybeing stronger bases than alkali metal ions, the two characteristicsrequired of the quaternary ammonium ion in the present invention.

This application is a continuation application of my prior applicationSerial No. 713,078 filed November 29, 1946, now abandoned.

All such modifications and departures in the invention are contemplatedas may fall within the scope of the appended claims.

What I claim is:

l. A bactericidally active deionizing agent for aqueous solutions, saidagent consisting of a chemical compound consisting of ethylene diaminetetraacetic acid having at least one of the carboxylic groupsneutralized by a basic bactericidally active quaternary ammonium ion andthe remaining carboxylic groups neutralized by alkali metal ions.

2. A bactericidally active deionizing agent for aqueous solutions, saidagent consisting of a chemical compound consisting of ethylene diaminetetracarboxylic acid having at least one of the carboxylic groupsneutralized by a basic 7 bactericidally active quaternary ammonium ion,another esterified by a glycerine and the remaining carboxylic groupsneutralized by alkali metal lens.

3. A bactericidally active deionizing agent for aqueous solutions, saidagent consisting of the monoto tetra-salt of ethylene diaminetetraacetic acid and dimethyl benzyl lauryl ammonium hydroxide.

4. The agent of claim 3, wherein said salt consiSts of the mono salt andwherein the remaining carboxylic groups of the tetra acid areneutralized by an alkali metal ion.

5. The agent of claim 3, wherein said salt consists of the mono salt ofsaid dimethyl benzyl lauryl ammonium hydroxide and wherein the remainingcarboxylic groups of the tetra acid are neutralized by sodium ions.

FREDERICK C. BERSWORTH.

8 REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,302,805 Schussler Nov. 24, 19422,317,999 Leuchs May 4, 1943 2,384,817 Chitwood Sept. 18, 1945 2,384,818Curme Sept. 18, 1945 2,428,353 Bersworth Oct. 7, 1947 OTHER REFERENCESBuntzinger, Zeit. Anorg. Chem., vol. 251, pp. 285-294 (1943).

Pfeiffer, Ber. Deut. Chem," vol. 763, pp. 847- 855 (1943).

Klemm, Zeit. Anorg. Chem, vol. 252, pp. 225- 226 (1944).

1. A BACTERICIDALLY ACTIVE DEIONIZING AGENT FOR AQUEOUS SOLUTIONS, SAID AGENT CONSISTING OF A CHEMICAL COMPOUND CONSISTING OF ETHYLENE DIAMINE TETRAACETIC ACID HAVING AT LEAST ONE OF THE CARBOXYLIC GROUPS NEUTRALIZED BY A BASIC BACTERICIDALLY ACTIVE QUATERNARY AMMONIUM ION AND THE REMAINING CARBOXYLIC GROUPS NEUTRALIZED BY ALKALI METAL IONS. 